1. Field of the Invention
The invention relates generally to insulated concrete form ("ICF") wall bracing, and more particularly, to a system and method for bracing an insulated concrete wall form to a support/bracing structure to align and support the ICF wall during construction.
2. Description of the Related Art
Conventional building construction utilizes concrete walls that are normally produced by constructing form walls, pouring concrete into the space between the walls and, upon setting of the concrete, removing the form walls. A conventional concrete form wall is disclosed in U.S. Pat. No. 4,333,289 to Strickland. The form wall includes a pair of spaced opposed panels made from plywood and defining therebetween a space into which soft concrete is poured in forming the wall. Horizontally spaced vertical stiffeners or strongbacks are provided outwardly of each plywood panel to provide major strengthening for the panel support structure. Elongate beams or walers are also provided to extend horizontally along the outer side of each panel. An outwardly opening pocket formed as part of the waler retains a wooden nailer to which the plywood form panel can be nailed, screwed or otherwise fastened to the waler.
Another system for temporarily attaching a reinforcing beam to a poured concrete structural member is shown in U.S. Pat. No. 5,572,838 to Truitt et al. An insert is adapted to be set in the poured concrete member. The insert has a body that creates a void in the concrete structural member and leg members that are partially set in the poured concrete with portions thereof extending through the body of the insert so as to be free of concrete. A special bolt engages with the leg members and provides a means for securing a reinforcement beam to the concrete structural member.
More recent building systems involve the use of insulated concrete forms (ICFs), which use a foam insulating material to construct permanent concrete form walls. The form walls are typically constructed by placing separate building components (also known as form blocks) upon each other. The concrete is then poured and the form walls are left in place after the concrete hardens to become a permanent part of the wall. Advantages provided by the use of ICFs include a reduction in the number of operations normally associated with building construction and generally the elimination of a need to provide further insulation. An example of particularly advantageous types of ICFs appears in U.S. Pat. Nos. 5,390,459; 5,657,600; and 5,809,727 to Mensen (Mensen), the disclosures of which are incorporated by reference herein in their entirety. In general, the ICFs taught by Mensen are made from a building component or block that includes first and second foam side panels. The side panels are preferably made of expanded polystyrene and are arranged in spaced parallel relationship with their inner surfaces facing each other. Plastic bridging members hold the side panels together against the forces applied by the poured concrete. Each bridging member includes end plates, which line up when the components are stacked to form furring strips for attachment of finishing materials.
With the advent of the use of stay-in-place forms or permanent concrete form work, such as ICFs, there is a need in the building construction art for an efficient, cost-effective and reliable apparatus and method to support the building components that make up the ICFs against construction loads. The insulated side panels of an ICF do not provide a strong surface to which reinforcing beams can be easily attached, as with plywood side panels. Commercial, institutional and industrial buildings often require walls higher than 8 to 9 feet in order to incorporate machinery, warehousing and high wall assemblies. Wall forms used in pouring in place such high vertical walls must be supported against various construction loads including wind loads, alignment loads, scaffold loads, and loads created by the hydrostatic pressure of the liquid concrete poured into the wall forms. Falsework is the construction industry term for structural supports and the necessary bracing required for the support of temporary loads during construction. Existing means for attaching strongbacks or reinforcing beams to wall forms do not lend themselves to the attachment of insulated panels on ICFs to conventional falsework.
Existing bracing systems used in ICF wall construction also do not adequately address the problems of supporting and controlling ICFs during construction, particularly in high wall applications of ICF (such as when the ICF is used to construct a wall of greater than 12 feet in height). For example, although conventional stage scaffolding has been used with ICFs, it is not recommended because it is a structure that generally must be braced itself, and is not designed for wind and other horizontal loads.
Accordingly, a bracing system such as shown in FIG. 3 has been used in ICF wall construction. This known system includes a vertical box channel 120 that is connected to the ICF blocks before they are filled with concrete using screws 122 that pass through the box channel 120 and into exposed end plates 124 of the plastic bridging members in the ICF blocks. As discussed above, the end plates 124 of each bridging member in the ICF blocks line up when the ICF blocks are stacked. The resulting "furring strip" provides the support for the vertical box channel 120. With walls reaching 12' to 14' high a 2".times.6" wooden board (not shown) can be screwed into the furring strip with screws that pass through vertical slots in the board. The board forms a "strong-back" that can extend the full height of the wall, and the vertical box channel 120 can be screwed into the board toward the top of the wall. A two-piece diagonal bracing pole 130 is joined at the threaded ends of each piece of the pole by a turnbuckle 132, which allows for adjustments in the length of pole 130. The diagonal pole is attached to the ground or sub-floor at one end 130', and to the box channel 120 at the opposite end 130". A standard scaffold angle 140 is also attached to the vertical box channel 120 to support scaffolding upright 150 and planks 152. Adjustments in the length of diagonal pole 130 by turning turnbuckle 132 result in end 130" of pole 130 either pushing or pulling on vertical box channel member 120, thus affecting the angle of the wall formed from the stacked ICF blocks. A disadvantage of this type of alignment system is that it requires the step of screwing a structural member such as vertical box channel 120 into the furring strips 124 or into a wooden board of strong-back that is in turn screwed into the furring strip, in order to provide a member for transferring loads such as wind loads from the ICF wall to bracing members such as diagonal pole 130. Furthermore, this system has height limitations, imposed by the standard length of 2".times.6" boards.
Hence, the foregoing discussion shows that there is a need for a temporary bracing system capable of supporting ICF walls during construction, particularly in high wall applications, that can be easily and reliably used with a variety of known falsework systems.